exam 2 ap info

What does the skeleton include and do?

• bone and cartilages

• supports internal organs

• protects internal organs

• Provides levers for movement by skeletal muscles

• stores lipids and mineral

• initial site of blood cell formation (hematopoiesis)

→ heme = blood

→ poiesis = forming

How may bones does the skeleton contain?

• 206

• divided into axial and appendicular

The axial skeleton includes?

1. head

2. neck

3. torso/trunk

• made up of bones that lie along the midline of the body

• includes: skull, hyoid, vertebrae, ribs, sternum, and sacrum

The appendicular skeleton includes?

• made up of bones that support the limbs and attach them to the skeleton.

• includes the pectoral girdles, upper limb, pelvic girdles, and lower limb.

What does the pectoral girdles include on the appendicular skeleton?

• clavicles (collar bone)

• scapulae (shoulder blade)

• innominate bones (os coxae)

For the classification of bone, what are the two different forms of osseous tissue?

compact bone and spongy bone

Bones are also classified by shape. Name the 6 shapes.

F.I.L.S.S.

1. flat

2. irregular

3. long

4. short

5. sesamoid

6. sutural (AKA wormian)

Long bones

→ most append. skeleton is made up of long bones

examples of long bone:

• femur

• phalanges

• metacarpals

What is the key characteristic structure of long bones?

• epiphysis (at the ends)

• diaphysis

→ two ends, called epiphysis and a shaft called diaphysis

Short bones

• roughly cubical

• they are primarily composed of spongy bone

• short bones include:

→ carpals

→ tarsals

Flat bones

• composed of two think layers of compact bone sandwiching a layer of spongy bone.

• Flat bones include the bones of the skull, the ribs, the scapulae, and the sternum.

Irregular bones

• Irregular bones are irregular in shape and do not fit into any other category.

• They are often made up of several components fused during development.

• the vertebrae and innominates are irregular bones.

Sesamoid bones

→ “seed shaped”

• sesamoid bones form within tendons

• the patella is the only sesamoid bone that is consistently present in all people.

• sesamoid bones are sometimes considered to be a subcategory of short bones.

Wormian bones

→ “wormy shaped”

• wormian (or sutural) bones form in the sutures of the skull.

• they are not present in all people in the same locations.

• they are sometimes to be considered a subcategory of flat bones.

Bone markings: What are the four categories?

1. projections for attachment of muscles or ligaments

2. projections that form joints

3. cavities

4. depressions or openings for the passage of blood vessels and nerves

→ projections for the attachment of muscles and ligaments will be important when we study the origins and insertions of muscles in exercise 15.

→ projections that form joints will be important when we study articulations in exercise 13.

• We will examine cavities (specifically

sinuses) when we examine the skull in

Exercise 10.

• Depressions and openings will be important

when we study the nervous system in

Exercises 19 and 21, and the blood vessels

next semester in Exercise 32.

Structure of bones

• individual bones are organs

• an organ is a discrete structure composed of two or more tissue types that performs a specific function.

• bones are composed of:

→ osseous connective tissue

→ dense irregular connective tissue

→ adipose connective tissue

→ and one or more types of cartilage

Structure of bones: Most bones contain both ____ and ____ forms of osseous connective tissue.

• compact

• spongy

Structure of bones: What is the function of compact bone?

provides strength along a single axis, bit is weak perpendicular to that axis

Structure of bones: What is the function of spongy bone?

provides limited strength in many directions and helps distribute forces

Compact bone is built from units called:

osteons

Compact bone:

An osteon (or Haversian system) is composed of a series of concentric rings called:

lamellae

Compact bone:

In between the lamellae, osteocytes sit within spaces called:

lacunae

Compact bone:

Osteocytes send cytoplasmic projections into the surrounding lamellae via ________.

Canaliculi

→ “little canals in the bone”

• these projections allow osteocytes to take up and deposit material from the lamellae

• they also allow osteocytes to receive nutrients form the blood supply of the bone

Compact bone:

Blood vessels and nerves travel through the __________ of the osteon.

central (or Haversian) canal of the osteon

→ up and down

Compact bone:

Blood vessels and nerves also travel perpendicular to the osteons via _________.

perforating (or Volkman’s) canal

→ L to R

Spongy bone is composed of bars of osseous tissue called ______.

trabeculae

Spongy bone:

Are trabeculae arranged like osteons?

NO

→ osteocytes sit within the lacunae inside the trabeculae and communicate with each other and the surface of the bar via canaliculi

Structure of long bones:

The typical long bones has a characteristic structure of two _______ separated by a ________.

• epiphyses (at the end)

• diaphysis (in the middle)

Structure of long bones:

The diaphysis is composed of compact bone surrounding a central ___________.

medullary cavity

→ medullary = for middle

Structure of long bones:

The epiphysis is composed of a spongy bone surrounded by a thin layer of ________.

compact bone

Structure of long bones:

The medullary cavity is filled with _______, an adipose tissue.

yellow marrow

Structure of long bones:

The spaces within the spongy bone of the epiphyses are filled with ________which is the site of hematopoiesis.

red marrow

→ hematopoiesis = new blood cells = red marrow

Structure of long bones:

The ______ line is the boundary between epiphysis and diaphysis.

epiphyseal line

• marks the zone of growth in length of long bones

Cartilage (fibrous, hyaline, elastin)

All cartilage contains ______ within lacunae.

chondrocytes

→ chondro = cartilage

→ cyte = cell

• the matrix is composed of ground substance and different types of protein fibers, depending on the particular variety of cartilage.

Cartilage:

What are the three types of cartilage?

1. Hyaline cartilage: has a uniform matrix without visible protein fibers

2. Elastic cartilage: has thick branched elastin fibers

3. Fibrous cartilage: has many parallel layers of collagen fibers

Cartilage:

Hyaline cartilage

• provides uniform structure but not much strength

• it forms the embryonic skeleton

• the articular surfaces of the long bones

• the costal cartilages (cartil. on rib)

• laryngeal and tracheal cartilages

Cartilage:

Elastic cartilage

• provides flexibility

• forms the cartilage of the external ear and the structure of the epiglottis

Cartilage:

Fibrous cartilage

• Fibrous cartilage provides great strength along a single axis.

• It allows for cushioning under heavy compression forces.

• It forms the intervertebral discs, the pubic symphysis, and the menisci of the knees.